function s1_read_last_two_bytes_of_a_mbr_backup_file(){
 local file_path=$1
 local last_bytes=$(tail -c 2 "$file_path" | od -A n -t x1 | tr -d '\n')
 if [ "$last_bytes" = "55aa" ];then
      echo "YES"
 else 
      echo "NO"
 fi
}

function s2_read_mbr_partition_table_info(){
 echo -n `echo "ibase=16; 800" | bc`
 echo -n ' '
 local mbr_backup_file=$1
 for i in {0..3}; do
 local offset=$((446 + i * 16))
 local partition_entry=$(od -j $offset -N 16 -t x1 -An "$mbr_backup_file" | tr -d '\n')
 local partition_type=$(echo $partition_entry | cut -c 9-10)
 if [ "$partition_type" != "00" ]; then
 local start_sector_hex=$(echo $partition_entry | cut -c 17-24 | tr '[:lower:]' '[:upper:]')
 local start_sector=$(echo "ibase=16;$start_sector_hex" | bc)
 local end_sector_size_hex=$(echo $partition_entry | cut -c 33-40 | tr '[:lower:]' '[:upper:]')
 local end_sector_size=$(echo "ibase=16;$end_sector_size_hex" | bc)
 local end_sector=$((start_sector + end_sector_size - 1))
 if [ $i -eq 0 ]; then
 echo -n "$end_sector"
 echo -n "$start_sector"
 else
 echo -n "$end_sector"
   fi
 fi
done

}

function s3_parse_partition_info(){
 fdisk_output=$(cat)
 disk_size_bytes=$(echo "$fdisk_output" | grep "Disk /dev/vda:" | awk '{print $5}')
 disk_size_sectors=$(echo "$fdisk_output" | grep "Disk /dev/vda:" | awk '{print $7}')
 physical_sector_size=$(echo "$fdisk_output" | grep "Sector size" | awk '{print $4}')
 first_partition_start_sector=$(echo "$fdisk_output" | grep "/dev/vda1" | awk '{print $3}')
 first_partition_end_sector=$(echo "$fdisk_output" | grep "/dev/vda1" | awk '{print $4}')
 first_partition_type=$(echo "$fdisk_output" | grep "/dev/vda1" | awk '{print $8}')
 echo "disk size in bytes:$disk_size_bytes"
 echo "disk size in sectors:$disk_size_sectors"
 echo "physical sector size in bytes:%physical_sector_size"
 echo "first partition start sector id:$first_partition_start_sector"
 echo "first partition end sector id:$first_partition_end_sector"
 echo "first partition type:$first_partition_type"
}

function s4_run_passwd_as_plain_user_and_get_status(){
 oversleeping_path=$(which oversleeping)
 chown root "$oversleeping_path"
 chmod 4755 "$oversleeping_path"
 oversleeping &
 ps -o uid,euid,ruid -C oversleeping | awk 'NR>1 {print $1","$2","$3}'
}

function s5_add_a_scheduled_task(){
 (crontab -l 2>/dev/null; echo "*/5**** echo \$(date +'%Y%m%d_%H%M%S') >> \$HOME/test_crontab") | crontab
}

